Patent GB-848071-A (GB)
Title: Improvements in phonographs having multiple stylus members
Filed: 1955-10-24
Abstract: 848,071. Phonographs. HANSEN, H. C. Oct. 22; 1956 [Oct. 24, 1955], No. 30366/55. Class 40 (2). In a multi-stylus gramophone pick-up, flexible stylus-holders 171 ... 173 are supported on, and biased against, a carrier 150 movable by controlmeans 156 selectively to bring each holder to engage the sensitive element 125 of the pick-up cartridge 120. As shown, the holders are cantilever springs substantially parallel or at a small acute angle to one another and all forming part of a single fork member 170 riveted at 160 to the support 150 pivoted at 151, 144 to a bracket 117, 130, 140, 142, a spring 146 on the pivot screw 145 biasing the support 150 to urge the arm of the knob 156 upwards into one of the notches 116a ... 116c; the pick-up element 125 projects into an aperture 153, and flexes the cantilever spring of that stylus immediately beneath it while the other springs remain against the edge of the aperture 153 and their styli are raised out of contact with the record. A side arm 190 is coupled by a rod 192 to balancing mechanism (not shown) to vary the stylus pressure on the record to suit each stylus. In a modification, the arm of the knob 156 projects vertically upwards through a slot in the top of the pick-up easing 110. In another form, cantilever stylus springs project radially inward from a support-ring or radially outward from a disc, the ring or disc being suspended from a manual control disc by two vertical arms straddling a fixed transverse bridge supporting the pick-up cartridge; the control-disc is first depressed (against a spring between it and the bridge) to withdraw radial ribs (corresponding to the styli) on its upper surface from notches in a fixed annular cover-plate, and to bring all the styli clear of the sensitive element of the pick-up; in this position it is rotated to bring the required stylus beneath the pick-up element, and on release the spring presses the ribs into the notches and raises all styli except one held down by the pick-up element. In a further form, Fig. 8, the stylus support-fork 370 has a substantially horizontal movement while the pickup element 325 moves vertically to depress positively the operative stylus; the fork 370 is secured by a support 350 to a casing 310 rotatable at one end in an annular groove 302 in the tone-arm front-plate 301, and at the other on a screw 345 supported by a bracket 340 to which the pick-up 320 is pivoted at 305; a pin 355 passes through a hole in the casing 310 and, as shown, locks it by engagement in one of a number of enlargements in a transverse slot 315 in a fixed part 342; by depressing the pin, the pick-up is tilted against a leaf-spring 346 to withdraw the element 325, and a neck 354 in the pin is brought into line with the slot 315; the easing 310 may then be rotated, the pin neck 354 passing through the narrow parts of the slot 315. The Provisional Specification refers to the coupling of a turn-over or tiltable pick-up to stylus-pressure adjusting means by means of a cam and push- or pull-rod, or crank, cord and spring means, or (in the case of a changeable pick-up head) co-operating transmission means at the rear of the head and at the front end of the tone-arm; the control-means therefor may be located at the rear end of the tone-arm, e.g. coupled to the turntable speed-control, or may be push-button-actuated through coupling- means engaged when the tone-arm is held in an appropriate position.